I am also want to make the same setup, with the same 150A bms (or maybe a 200A bms like THIS).
After I read more here on the forum, i am not sure, do we need an active balancer too.... or not?
i've read it here
i have also spoke with a JBD reseller, asking if I can use 2x 200A BMS for 2x200AH batteries, and they said that current after paralel connection can't exceed 200A.
From what I know, if you have 2x120A BMS, your max discharge rate is 75% from 240A. So only 180A.
later edit: it was about lithium batteries, parallel connections provide 75% of power output